title: Development of an attached-growth process for the on-site bioremediation of an aquifer polluted by chlorinated solvents.
abstract: A procedure for the design of an aerobic cometabolic process for the on-site degradation of chlorinated solvents in a packed bed reactor was developed using groundwater from an aquifer contaminated by trichloroethylene (TCE) and 1,1,2,2-tetrachloroethane (TeCA). The work led to the selection of butane among five tested growth substrates, and to the development and characterization from the site's indigenous biomass of a suspended-cell consortium capable to degrade TCE (first order constant: 96 L gprotein(-1) day(-1) at 30 °C and 4.3 L gprotein(-1) day(-1) at 15 °C) with a 90 % mineralization of the organic chlorine. The consortium immobilization had strong effects on the butane and TCE degradation rates. The microbial community structure was slightly changed by a temperature shift from 30 to 15 °C, but remarkably affected by biomass adhesion. Given the higher TCE normalized degradation rate (0.59 day(-1) at 15 °C) and attached biomass concentration (0.13 gprotein Lbioreactor(-1) at 15 °C) attained, the porous ceramic carrier Biomax was selected as the best option for the packed bed reactor process. The low TeCA degradation rate exhibited by the developed consortium suggested the inclusion of a chemical pre-treatment based on the TeCA to TCE conversion via β-elimination, a very fast reaction at alkaline pH. To the best of the authors' knowledge, this represents the first attempt to develop a procedure for the development of a packed bed reactor process for the aerobic cometabolism of chlorinated solvents.
authors.affiliation: Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Via Terracini 28, 40131, Bologna, Italy, dario.frascari@unibo.it.
authors.forename: Dario
authors.initials: D
authors.lastname: Frascari
authors.forename: Giacomo
authors.initials: G
authors.lastname: Bucchi
authors.forename: Francesco
authors.initials: F
authors.lastname: Doria
authors.forename: Antonella
authors.initials: A
authors.lastname: Rosato
authors.forename: Nasrin
authors.initials: N
authors.lastname: Tavanaie
authors.forename: Raffaele
authors.initials: R
authors.lastname: Salviulo
authors.forename: Roberta
authors.initials: R
authors.lastname: Ciavarelli
authors.forename: Davide
authors.initials: D
authors.lastname: Pinelli
authors.forename: Serena
authors.initials: S
authors.lastname: Fraraccio
authors.forename: Giulio
authors.initials: G
authors.lastname: Zanaroli
authors.forename: Fabio
authors.initials: F
authors.lastname: Fava
mesh_terms: D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors; D002073:Butanes / Q000378:metabolism*; D004980:Ethane / Q000031:analogs & derivatives* / Q000378:metabolism; D060587:Groundwater / Q000737:chemistry / Q000382:microbiology*; D006843:Hydrocarbons, Chlorinated / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D059013:Microbial Consortia / Q000502:physiology*; D013696:Temperature; D014241:Trichloroethylene / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D002073:Butanes; D006843:Hydrocarbons, Chlorinated; D014874:Water Pollutants, Chemical; C015530:1,1,2,2-tetrachloroethane; D014241:Trichloroethylene; C046888:butane; D004980:Ethane